<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head>
<title>Javascript Debugging with Firebug</title>
<script type="text/javascript">
    function doSomething(){
        var lbl = document.getElementById('messageLabel');
        lbl.innerHTML = "I just did something.";
    }
</script>
</head>
<body>
    <div>
        <div id="messageLabel"></div>
        <input type="button" value="Click Me!" onclick="doSomething();" />
    </div>
</body>
</html>